Grazing *does* rebuild organic matter. Cow guts break tough plant parts into nice soft squishy soil parts.
Without OM, dirt is just sand & clay. Either it's way too tight & doesn't let roots through, or it's super loose & can't hang onto water.
In tight clay soils, also gives the soil more "spring" so it doesn't turn into a mud slick after rains.
(note: nobody @ me about soil microflora, this thread is the reader's digest version)
"Good soil" starts at about 2% OM. Soils with less than that get noticeably hard to work with.
If you go above 2%, you're living fat & happy.
Every 1% OM you can add to soil sequesters 2-3 tons of carbon from the atmosphere.
So if you wanna have high-OM soil, you have to keep adding OM as fast or faster than it breaks down into CO2.
They're walking shit factories and I say that with the highest respect
That rich prairie soil? Kiiiiinda comes from the grass.
But really, it's millennia worth of bison poop. That we're just kinda mining right now til it runs out.
Conversion of soil OM into CO2 dwarfs every other source of CO2 that goes into the atmosphere.
Which means YOU DON'T HAVE TO WAIT FOR TREATIES AND GOV'TS TO GET THEIR SHIT TOGETHER. YOU CAN JUST. DO IT.
I've been to farms where the soil's just dried-up white beach sand w 0% OM (ah, FL).
But their neighbor who runs pastured cattle's got thick, moist, chocolate cake-looking dirt at 4-5% OM.
...cutting down forests to raise cows is a non-winner, carbon-wise